The present invention relates to a tempering installation for shaped workpieces in a thin layer particularly for long cylindrical pieces such as drive shafts and cam shafts for automobile engines.
Tempering systems for workpieces leaving a furnace usually fit in two categories; tempering in bulk in which apparatus for lifting the pieces from the cooler are provided and tempering of ordered workpieces which is the only way for tempering long workpieces. Other than tempering arrangements usually provided for the automatic manufacture of workpieces of variable dimension such as helicoidal springs, tempering structures are known for long workpieces in which the pieces are arranged on supports descending in the bath or reversed on a false plateau at the transfer conveyor. A tempering installation is also known for long pieces which utilizes a furnace employing an endless carrying table above the end of which is disposed a bin extended by a horizontal channel provided with an opening for the pieces falling in a bath on a lifting table. A tempering process is also known for long pieces associated with heating apparatus utilizing induction which consist in mounting in parallel an induction assembly and a tempering assembly in such a way that a passage from one to the other occurs rapidly and automatically.
All of these known structures have certain advantages but there are also inconveniences which essentially are that they are designed and operated for a predetermined workpiece and the replacement of a workpiece to be treated by another of different size or configuration necessitates an important modification of the support of the workpiece in the tempering bath and of the manipulation structure for the workpieces. Another inconvenience of known structures and systems relates to the tempering method. It is known the the process referred to as tempering in a thin layer has advantages on the plan of duration of tempering; of the quality of the tempered product; and of the cost of the operation. Known systems do not assure tempering in thin layer of long pieces under optimum conditions. The present invention provides a solution to these problems and allows for the interchangeability of the workpieces to be tempered because the central tempering unit is movable and can receive a tempering mounting preregulated as a function of the workpieces that it receives. The present invention also provides for tempering in a thin layer of the workpieces in that it utilizes supporting mechanisms and particular means which limit the thickness of the layer of tempering liquid to an appropriate value.